DNA, genes and chromosomes

Question 1

What does a DNA nucleotide consist of?

Answer 1

Phosphate group, Pentose sugar (deoxyribose), and a nitrogen-containing base

Question 2

What is the Pentose sugar RNA?

Answer 2

Ribose sugar

Question 3

What are the 4 bases?

Answer 3

A- adenine, g-guanine, c-cytosine, t-thymine (in RNA this is uracil)

Question 4

What 2 bases are purines(double-ring structure)?

Answer 4

Adenine & guanine

Question 5

What 2 bases are pyramidines (single ring structures)?

Answer 5

Cytosine & thymine

Question 6

How are polynucleotides formed?

Answer 6

Condensation reaction forms a phosphodiester bond between hydroxyl group of one nucleotide and phosphate group of next nucleotide

Question 7

Describe structure of DNA.

Answer 7

Two polynucleotide strands held together by hydrogen bonds between bases. Bases on each strand complementary to one another. Two strands are anti-parallel and twist around each other to form a double-helix structure.

Question 8

Give 3 features of DNA

Answer 8

Found in nucleus
Long molecule
Double - stranded

Question 9

Give 3 features of RNA.

Answer 9

Found in cytoplasm
Relatively short molecule
Single-stranded

Question 10

Give 3 features of mRNA

Answer 10

Made during transcription
Single poly nucleotide strand
Groups op 3 adjacent bases called a codon

Question 11

Structure of tRNA

Answer 11

Involved in translation
Single polynucleotide strand folded into clover shape
Hydrogen bonds between specific base pairs hold its shape.
Has a specific sequence of bases called anti-codon at one end.
Have an amino acid binding site on the other end.

Question 12

Give the features of eukaryotic DNA

Answer 12

-Linear molecule that exist as chromosomes in the nucleus
- wound up around proteins called histones that package and order to DNA form chromosomes
- mitochondria and chloroplasts have their own DNA similar to prokaryotic DNA

Question 13

Give features of prokaryotic DNA

Answer 13

DNA is circular
Not wound around histones - condenses to fit in cell through supercoiling

Question 14

What is a gene?

Answer 14

Sequence of DNA bases that codes for a polypeptide chain or functional RNA. Forms primary structure of a protein.

Question 15

What is a triplet?

Answer 15

Three bases that code for an amino acid

Question 16

What is functional RNA?

Answer 16

Genes that don’t code for a polypeptide chain.

Question 17

What is a genome?

Answer 17

Complete set of genes in a cell.

Question 18

What is a proteome?

Answer 18

Full range of proteins that the cell is able to produce.

Question 19

What are introns?

Answer 19

Part of genes that don’t code for amino acids

Question 20

What are exons?

Answer 20

All parts of a gene that code for proteins

Question 21

What are non-coding repeats?

Answer 21

Non-coding DNA that can be found between genes

Question 22

Why is DNA replication semi-conservative?

Answer 22

Half the strands in each new DNA molecule are from the original DNA molecule.

Question 23

Step 1 of DNA replication

Answer 23

Enzyme DNA Helicase breaks hydrogen bonds between bases unwinding DNA to form 2 separate strands.

Question 24

Step 2 of DNA replication

Answer 24

Each original strand acts as a template strand. Free nucleotides attract to complementary bases on the template strand - A-T G -C

Question 25

Step 3 of DNA replication

Answer 25

Condensation reactions join nucleotides of new strands. Phosphodiester bonds formed and catalysed by DNA polymerase. Hydrogen bonds form between bases. Each DNA molecule contains a strand from the original DNA molecule.